Bronze Mortar Model Marked "1530"

[cannonmn]

What really bothers me about our mortar in discussion is the striking crispness of the concentric circles on the bottom and of the trunnions.

Thanks Michael. Well we know who ever made this used a metal-cutting lathe to make the two concentric rings on the muzzle and the very fine lines around the mid-section. They must have a very sharp, hardened steel cutter in use on that lathe, so the concentric circles on the base came from the same cutter. The divot in the center of the bottom is of course where the lathe center was positioned, and had to be drilled there before the lathe-turning could begin.

I don't know when precise metal-cutting lathes were first used, do you? What I know for sure is that this piece was completed with a very precise metal-cutting lathe.